Operation appropriateness determination system, method for determining operation appropriateness, and non-transitory computer readable medium storing program for determining operation appropriateness

ABSTRACT

An operation appropriateness determination system includes an authentication apparatus that identifies an operator on a basis of a feature of the operator and that outputs information for identifying the operator, a biometric sensing apparatus that obtains biological information regarding the operator and that outputs the biological information, an operation sensing apparatus that detects a load of an operation that is being performed by the operator and that outputs operation information indicating the load of the operation, a storage device, and a signal processing apparatus.

BACKGROUND 1. Technical Field

The present invention relates to a system that determines currentoperation appropriateness of an operator, a method, and a non-transitorycomputer readable medium storing a program.

2. Description of the Related Art

Mental concentration is extremely important in daily operations. If aperson performs an operation without attention, efficiency decreases,and an accident can be caused. If a person loses concentration during anoperation, for example, operation efficiency decreases, and productivityalso decreases. Lack of concentration or sleepiness during driving of avehicle can directly lead to a traffic accident. If concentration can beconstantly monitored and an appropriate advice or assistance can beprovided in accordance with a degree of concentration or nervousness atthe time, operation efficiency or safety can improve. A large number ofsuch measures have actually been proposed. A technique for determining adegree of mental concentration from various types of biologicalinformation and providing an advice or assistance in accordance with thedegree of concentration, for example, has been proposed. JapaneseUnexamined Patent Application Publication No. 2002-65650, JapanesePatent No. 6003782, and Japanese Patent No. 5119375 have disclosedexamples of such a technique.

SUMMARY

In one general aspect, the techniques disclosed here feature anoperation appropriateness determination system including anauthentication apparatus that identifies an operator on a basis of afeature of the operator and that outputs information for identifying theoperator, a biometric sensing apparatus that obtains biologicalinformation regarding the operator and that outputs the biologicalinformation, an operation sensing apparatus that detects a load of anoperation that is being performed by the operator and that outputsoperation information indicating the load of the operation, a storagedevice, and a signal processing apparatus. The signal processingapparatus accumulates, while the operator is performing the operation,the information for identifying the operator, the biologicalinformation, the operation information, and time information in thestorage device while associating the information for identifying theoperator, the biological information, the operation information, and thetime information with one another, estimates the biological informationregarding the operator at a present time on a basis of a correlationbetween temporal changes in the operation information and temporalchanges in the biological information in past accumulated in the storagedevice, and determines appropriateness of the operator for the operationby comparing the estimated biological information regarding the operatorat the present time and the biological information regarding theoperator at the present time obtained by the biometric sensing apparatuswith each other.

It should be noted that general or specific aspects of the presentdisclosure may be implemented by a device, an apparatus, a system, amethod, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram illustrating the configuration of an operationappropriateness determination system according to an exemplaryembodiment of the present disclosure;

FIG. 1B is a diagram illustrating an example of the operation of theoperation appropriateness determination system according to theexemplary embodiment of the present disclosure;

FIG. 2 is a diagram illustrating individual differences in biologicalreactions to stress;

FIG. 3A is a diagram illustrating an imaging device for which a lightsource that emits light having a uniform distribution is used;

FIG. 3B is a diagram illustrating a concept of an imaging device forwhich a light source that emits temporally modulated light is used;

FIG. 3C is a diagram illustrating a concept of an imaging device forwhich a light source that emits spatially modulated light is used;

FIG. 4A is a diagram illustrating an example of arrangement of anoperation appropriateness determination system according to a firstembodiment of the present disclosure;

FIG. 4B is a diagram illustrating an outline of a cerebral blood flowmeasuring apparatus according to the first embodiment of the presentdisclosure;

FIG. 5 is a diagram illustrating the configuration of the operationappropriateness determination system according to the first embodimentof the present disclosure;

FIG. 6 is a diagram illustrating an example of calculation of anoperation load of driving;

FIG. 7 is a diagram illustrating measured values of changes in cerebralblood flow during a driving task;

FIG. 8A is a first diagram illustrating a method for estimating cerebralblood flow;

FIG. 8B is a second diagram illustrating the method for estimatingcerebral blood flow;

FIG. 8C is a third diagram illustrating the method for estimatingcerebral blood flow;

FIG. 9A is a diagram illustrating estimated changes in cerebral bloodflow and measured changes in cerebral blood flow during normal driving;

FIG. 9B is a diagram illustrating estimated changes in cerebral bloodflow and measured changes in cerebral blood flow in a state withoutdriving appropriateness;

FIG. 10A is a diagram illustrating an example of arrangement of a systemfor measuring operation stress according to a second embodiment of thepresent disclosure;

FIG. 10B is a diagram illustrating an example of the configuration of acerebral blood flow measuring apparatus according to the secondembodiment;

FIG. 11A is a first diagram illustrating signal processing for obtainingbiological information according to the second embodiment;

FIG. 11B is a second diagram illustrating the signal processing forobtaining biological information according to the second embodiment;

FIG. 11C is a third diagram illustrating the signal processing forobtaining biological information according to the second embodiment;

FIG. 12 is a diagram illustrating an example of a relationship betweenan operation condition and biological information during an operation;

FIG. 13A is a diagram illustrating a distribution of biologicalinformation and operation information estimated on the basis of data fora long period of time;

FIG. 13B is a diagram illustrating an example of a distribution ofmeasured biological information;

FIG. 13C is a diagram illustrating another example of the distributionof measured biological information;

FIG. 14A is a first diagram illustrating signal processing for obtainingbiological information according to a third embodiment;

FIG. 14B is a second diagram illustrating the signal processing forobtaining biological information according to the third embodiment; and

FIG. 14C is a third diagram illustrating the signal processing forobtaining biological information according to the third embodiment.

DETAILED DESCRIPTION

The present disclosure includes an operation appropriatenessdetermination system, a method, and a computer program described in thefollowing items.

Item 1

An operation appropriateness determination system according to Item 1 ofthe present disclosure includes:

an authentication apparatus that identifies an operator on a basis of afeature of the operator and that outputs information for identifying theoperator;

a biometric sensing apparatus that obtains biological informationregarding the operator and that outputs the biological information;

an operation sensing apparatus that detects a load of an operation thatis being performed by the operator and that outputs operationinformation indicating the load of the operation;

a storage device; and

a signal processing apparatus.

The signal processing apparatus

accumulates, while the operator is performing the operation, theinformation for identifying the operator, the biological information,the operation information, and time information in the storage devicewhile associating the information for identifying the operator, thebiological information, the operation information, and the timeinformation with one another,

estimates the biological information regarding the operator at a presenttime on a basis of a correlation between temporal changes in theoperation information and temporal changes in the biological informationin past accumulated in the storage device, and

determines appropriateness of the operator for the operation bycomparing the estimated biological information regarding the operator atthe present time and the biological information regarding the operatorat the present time obtained by the biometric sensing apparatus witheach other.

Item 2

In the operation appropriateness determination system according to Item1,

the authentication apparatus may include an input device that enablesthe operator to input a person authentication code before performing theoperation, and

the authentication apparatus may identify the operator on a basis of theperson authentication code.

Item 3

In the operation appropriateness determination system according to Item1,

the authentication apparatus may include a biometric authenticationdevice that identifies the operator using at least one selected from thegroup consisting of a fingerprint, a palm print, an iris, and a veinpattern.

Item 4

The operation appropriateness determination system according to Item 1,may further include:

an imaging device that captures an image of the operator and thatobtains data regarding the image.

The authentication apparatus may identify the operator on a basis of thedata regarding the image.

Item 5

In the operation appropriateness determination system according to anyof Items 1 to 4,

the biometric sensing apparatus

may be arranged at a point distant from the operator,

include an imaging element that captures an image including a head ofthe operator and that obtains data regarding the image, and

obtain the biological information regarding the operator on a basis ofthe data regarding the image.

Item 6

In the operation appropriateness determination system according to anyof Items 1 to 4,

the biometric sensing apparatus may include

a light source that emits near-infrared light which is spatially ortemporally modulated, and

an imaging element that captures an image including a face of theoperator illuminated by the light source.

Item 7

In the operation appropriateness determination system according to Item6,

the near-infrared light may be spatially modulated using a dot arraypattern, a line-space pattern, or a checker pattern.

Item 8

In the operation appropriateness determination system according to Item6,

the near-infrared light may be pulsed light, and

the imaging element may include at least one charge accumulator thatreceives the pulsed light and that accumulates signal charge.

Item 9

In the operation appropriateness determination system according to anyof Items 1 to 8,

the signal processing apparatus may estimate the biological informationregarding the operator at the present time by analyzing the correlationaccumulated in the storage device through a multivariate analysis.

Item 10

In the operation appropriateness determination system according to anyof Items 1 to 8,

the signal processing apparatus may learn the correlation stored in thestorage device through machine learning and estimates the biologicalinformation regarding the operator at the present time on a basis of alearning result.

Item 11

In the operation appropriateness determination system according to anyof Items 1 to 10,

the operator may be a driver of a vehicle,

the operation may be driving of the vehicle, and

the operation information may be information regarding an operation fordriving the vehicle.

Item 12

In the operation appropriateness determination system according to Item11,

the operation for driving the vehicle may include at least one operationselected from the group consisting of acceleration, braking, andsteering.

Item 13

In the operation appropriateness determination system according to Item11 or 12,

the operation sensing apparatus may include an acceleration sensor, and

the signal processing apparatus may estimate information regarding theoperation for driving the vehicle on a basis of information output fromthe acceleration sensor.

Item 14

In the operation appropriateness determination system according to anyof Items 11 to 13,

the vehicle may have an autonomous driving function including drivingassistance, and

the signal processing apparatus may determine content of the drivingassistance in accordance with the appropriateness of the driver andcause the vehicle to perform the driving assistance.

Item 15

In the operation appropriateness determination system according to anyof Items 1 to 10,

the operation may be an input operation in which a computer is used, and

the operation information may be information regarding an operationinput to the computer.

Item 16

In the operation appropriateness determination system according to Item15,

the operation may include at least one operation selected from the groupconsisting of a keyboard input and a mouse operation.

Item 17

In the operation appropriateness determination system according to Item15 or 16,

the signal processing apparatus may cause the computer to output animage or a sound indicating advice about the input operation inaccordance with the appropriateness of the operator.

Item 18

In the operation appropriateness determination system according to anyof Items 1 to 10,

the operation may be learning in which a computer is used, and

the operation information may be information regarding content of thelearning and an operation performed using the computer.

Item 19

In the operation appropriateness determination system according to Item18,

the signal processing apparatus may cause the computer to providelearning content according to the appropriateness of the operator.

Item 20

A method for determining appropriateness of an operator for an operationaccording to Item 20 of the present disclosure includes:

obtaining information for identifying the operator, biologicalinformation regarding the operator who is performing the operation, andoperation information indicating a load of the operation;

accumulating the information for identifying the operator, thebiological information, the operation information, and time informationin a storage device while associating the information for identifyingthe operator, the biological information, the operation information, andthe time information with one another;

estimating the biological information regarding the operator at apresent time on a basis of a correlation between temporal changes in theoperation information and temporal changes in the biological informationin past accumulated in the storage device; and

determining the appropriateness of the operator for the operation at thepresent time by comparing the estimated biological information regardingthe operator at the present time and the obtained biological informationregarding the operator at the present time.

Item 21

A non-transitory computer readable medium according to Item 21 of thepresent disclosure stores a computer program causing a computer toperform a process including:

obtaining information for identifying an operator, biologicalinformation regarding the operator who is performing an operation, andoperation information indicating a load of the operation;

accumulating the information for identifying the operator, thebiological information, the operation information, and time informationin a storage device while associating the information for identifyingthe operator, the biological information, the operation information, andthe time information with one another;

estimating the biological information regarding the operator at apresent time on a basis of a correlation between temporal changes in theoperation information and temporal changes in the biological informationin past accumulated in the storage device; and

determining appropriateness of the operator for the operation at thepresent time by comparing the estimated biological information regardingthe operator at the present time and the obtained biological informationregarding the operator at the present time.

Embodiments that will be described hereinafter are general or specificexamples. Values, shapes, materials, components, positions at which thecomponents are arranged, and the like mentioned in the followingembodiments are examples, and do not limit the techniques in the presentdisclosure. Among the components described in the following embodiments,ones not described in the independent claims, which define broadestconcepts, will be described as optional components.

In the present disclosure, some or all of circuits, units, apparatuses,members, or sections or some or all of functional blocks illustrated inthe block diagrams, for example, may be achieved by one or a pluralityof electronic circuits including a semiconductor device, a semiconductorintegrated circuit (IC), or an large-scale integration (LSI) circuit.The LSI circuit or the IC may be integrated on a single chip, or may beobtained by combining a plurality of chips. The functional blocks otherthan storage devices, for example, may be integrated on a single chip.Although the term “LSI” or “IC” is used here, “system LSI”,“very-large-scale integration (VLSI)”, or “ultra-large-scale integration(ULSI)” may be used depending on a degree of integration. Afield-programmable gate array (FPGA), which is programmed after an LSIcircuit is fabricated, or a reconfigurable logic device, in whichconnections inside an LSI circuit can be reconfigured or circuitsections inside the LSI can be set up, may be used for the samepurposes.

Furthermore, functions or operations of some or all of the circuits, theunits, the apparatuses, the members, or the sections may be achievedthrough software processes. In this case, software is stored in one or aplurality of non-transitory storage media, such as read-only memories(ROMs), optical discs, or hard disk drives, and functions specified bythe software are achieved by a processor and peripheral apparatuses whenthe processor has executed the software. A system or an apparatus mayinclude the one or plurality of non-transitory storage media in whichthe software is stored, the processor, and necessary hardware devices,such as interfaces.

Underlying Knowledge Forming Basis of the Present Disclosure

Underlying knowledge forming a basis of the present disclosure will bedescribed before the embodiments of the present disclosure will bedescribed.

As described above, whether a mental state of a person during anoperation is appropriate for the operation is an extremely importantfactor that influences not only efficiency of the operation but alsosafety of the operation. Various measures have therefore been taken toestimate mental states. Various types of biological information havebeen detected in order to estimate mental states such as nervousness,vigilance, and concentration. Biological information such as a heartrate, fluctuation in a heart rate, a respiratory rate, fluctuation in arespiratory rate, the depth of respiration, blood pressure, brain waves,cerebral blood flow (CBF), pupil diameter, nose temperature, blinking,and movement of a line of sight has been used. There are, however,roughly three major problems in methods for directly estimating a mentalstate from such biological information.

A first problem is individual differences in biological reactions. Evenif the accuracy of an operation remains substantially the same, or evenif a degree of vigilance or concentration measured on the basis of aninterview with a person remains substantially the same, how biologicalreactions appear greatly varies between individuals. A person's mentalstate cannot be correctly estimated by simply measuring biologicalinformation.

A second problem is stability. Even with the same subject, biologicalreactions might differ depending on an environment during measurement, atype of activity performed before the measurement, or an operationhistory. Even when a subjected is limited to a particular person, it isdifficult to accurately estimate a mental state of the person only onthe basis of biological reactions during measurement.

A third problem is an inspection method. A method is usually used inwhich certain stimuli are given to a subject and a mental state isestimated from biological reactions to the stimuli. In a laboratory, acertain task (e.g., mathematical calculations, quizzes, or directstimuli to a body) can be assigned in a fixed environment and biologicalreactions to the certain task can be measured. During an actualoperation, however, an operation environment and content of theoperation can greatly vary. It is not easy to estimate a mental state ofan operator in real-time under such a condition.

FIG. 2 is a diagram illustrating individual differences in changes inbiological information and variation between measurement operations at atime when a task was performed. Here, a calculation task was assigned toeach subject, and a degree of stress caused by the task was measured onthe basis of fluctuation in a heart rate while the subject was relaxedor performing the task. The stress at this time is also called“vigilance”. A heart rate constantly fluctuates. A high-frequencycomponent of the fluctuation in variation in the heart rate is said tobe affected by the activity of a parasympathetic nervous system causedby respiration. A low-frequency component, on the other hand, is said tobe affected by the activity of both a sympathetic nervous system and theparasympathetic nervous system. In this example, a range of thehigh-frequency component was equal to or higher than 0.20 Hz but lowerthan 0.35 Hz, and a range of the low-frequency component was equal to orhigher than 0.05 Hz but lower than 0.20 Hz. A value indicating a ratioof the high-frequency component of fluctuation in the heart rate isdenoted by HF, and a value indicating a ratio of the low-frequencycomponent is denoted by LF. When a person is stressed or nervous, LF/HFincreases. For this reason, this value can be used as an indicator ofstress or nervousness.

ΔLF/HF of a vertical axis illustrated in FIG. 2 indicates the amount ofchange in LF/HF before and after a task is performed. Resultsillustrated in FIG. 2 indicate that ΔLF/HF exceeds zero (0) with someexceptions. It can be seen from these results that LF/HF tends toincrease due to stress or nervousness. The amount of increase, however,becomes smaller as the age of a subject increases.

Solid circles in FIG. 2 indicate results of a plurality of testsconducted on the same person. It can be seen that variation betweentests was great even with the same person.

The results illustrated in FIG. 2 were obtained under limitedconditions, that is, obtained when a certain task was assigned to eachsubject. During an actual operation, however, content of an operation,that is, a task, is not constant. When content of an operation varies,biological information accordingly varies. It is therefore difficult todetermine operation appropriateness of an operator during an actualoperation only on the basis of measured values of biologicalinformation. The “operation appropriateness” refers to a degree of amental state in which an operator can efficiently perform an operationwithout errors. Operation appropriateness refers to a degree of a mentalstate, such as vigilance, nervousness, attention, or concentration.

A system is possible in which an operator is asked to stop performing anoperation and perform a certain judgment task and operationappropriateness is determined from a result of the judgment task. It is,however, not realistic to incorporate such a task during an actualoperation. Such a system is therefore not widely used.

The present disclosure provides a novel technique for stably estimatinga mental state of an operator during an operation. According to theembodiments of the present disclosure, an operation load is monitoredand a relationship between the operation load and biological informationis learned for each operator. By using data accumulated through aplurality of learning processes, changes in biological informationcaused by an operation can be estimated.

FIG. 1A is a diagram illustrating the configuration of an operationappropriateness determination system according to an exemplaryembodiment of the present disclosure. An operation appropriatenessdetermination system 100 includes an authentication apparatus 101, anoperation sensing apparatus 102, a biometric sensing apparatus 106, asignal processing apparatus 108, a storage device 104, and a displayapparatus 107. The signal processing apparatus 108 includes a biologicalinformation estimation unit 103 and an operation appropriatenessdetermination unit 105.

In the present embodiment, persons are authenticated at beginnings ofoperations, and a database is built for each person. In the database,information indicating a load of each operation (referred to as“operation information” herein) and biological information obtainedduring the operation are associated with each other for the operation.The operation information may include content of the operation. By usingstored data, an effect of individual differences in biologicalinformation can be reduced, and operation appropriateness can be stablydetermined regardless of the operator.

Personal authentication is performed, for example, when an operatorinputs an operator identifier (ID) at a beginning of an operation or theauthentication apparatus 101 performs biometric authentication. Thebiometric authentication can be performed, for example, using a methodsuch as face recognition, fingerprint recognition, iris recognition, orvein recognition. In a mode in which the operator inputs a personalauthentication code such as an operator ID, the authentication apparatus101 can be an apparatus including an input device, such as a mobileinformation terminal or a personal computer (PC). The input device caninclude, for example, at least either a keyboard or a mouse. In a modein which the authentication apparatus 101 performs biometricauthentication, the authentication apparatus 101 is an apparatus havinga function of performing biometric authentication such as facerecognition, fingerprint recognition, iris recognition, or veinrecognition. In the latter mode, the authentication apparatus 101includes one or more biometric authentication devices necessary forpersonal authentication, such as a camera or a fingerprint sensor.

The operation sensing apparatus 102 monitors current operationconditions of an operator and outputs operation information indicating aload of an operation. The configuration of the operation sensingapparatus 102 varies depending on the content of the operation. If theoperation is driving of a vehicle, for example, the operation sensingapparatus 102 can include a sensor such as an acceleration sensor or anangular velocity sensor. If the operation is office work or learning forwhich a computer is used, the operation sensing apparatus 102 caninclude the computer or an input device of the computer.

The biometric sensing apparatus 106 continuously or intermittentlymeasures biological information regarding an operator during anoperation. The biological information obtained by the biometric sensingapparatus 106 is biological information that has been actually measured.For this reason, the biological information will also be referred to as“measured biological information”. The biometric sensing apparatus 106may obtain biological information regarding an operator in a noncontactmanner. When the biometric sensing apparatus 106 obtains biologicalinformation regarding an operator in a noncontact manner, the biologicalinformation can be obtained even if it is difficult for the operator towear a device of a contact type because of the content of an operation.The use of the noncontact biometric sensing apparatus 106 also reducesawkwardness and uncomfortableness that would otherwise be caused bywearing of a biological sensor.

The storage device 104 stores measured biological information andobtained databases of operation information for different persons. Ineach database, data is accumulated for each person and for eachoperation. The storage device 104 can include a storage medium such as aflash memory, a magnetic disk, or an optical disc.

The signal processing apparatus 108 can be achieved, for example, by adigital signal processor (DSP), a programmable logical device (PLD) suchas a field-programmable gate array (FPGA), or a combination of a centralprocessing unit (CPU) and a computer program. The signal processingapparatus 108 may be a component of an external apparatus such as aserver provided at a remote place. In this case, the external apparatussuch as a server includes communication means and communicates data withthe authentication apparatus 101, the operation sensing apparatus 102,the biometric sensing apparatus 106, the storage device 104, and thedisplay apparatus 107.

The signal processing apparatus 108 includes the biological informationestimation unit 103 and the operation appropriateness determination unit105. These components can be achieved when the signal processingapparatus 108 has executed a computer program stored in the storagedevice 104. Alternatively, these components may be discrete circuitsconfigured to perform operations that will be described hereinafter.

The biological information estimation unit 103 estimates currentbiological information regarding an operator on the basis of the dataaccumulated in the storage device 104. The estimated biologicalinformation is a value of current biological information estimated onthe basis of operation loads and biological information regarding theoperator obtained in the past. For this reason, this information will bereferred to as “estimated biological information”. The operationappropriateness determination unit 105 compares estimated biologicalinformation and measured biological information regarding an operatorwith each other and determines operation appropriateness on the basis ofa result of the comparison. A specific example of a process performed bythe biological information estimation unit 103 and the operationappropriateness determination unit 105 will be described later.

If there is no abnormality in an operator, estimated biologicalinformation based on past data substantially matches measured currentbiological information. If there is an abnormality in an operator, onthe other hand, a change larger than a value of variation calculatedfrom past data is caused between estimated biological information andmeasured biological information. In this case, the operationappropriateness determination unit 105 determines that operationappropriateness is not enough. In this case, the operationappropriateness determination unit 105 causes the display apparatus 107to display an advice, a warning, or the like to the operator.Alternatively, the operation appropriateness determination unit 105 mayforcibly stop the operation. Forcible stopping of an operation is aprocess for stopping an apparatus or a system. Alternatively, a speakermay be provided instead of, or in addition to, the display apparatus107, and the operation appropriateness determination unit 105 may causethe speaker to output a sound of an alert or an advice.

Next, an example of the overall operation of the operationappropriateness determination system will be described with reference toFIG. 1B.

FIG. 1B is a flowchart illustrating an example of the operation of theoperation appropriateness determination system. The system performs theoperation illustrated in FIG. 1B for each operation.

First, in step S101, the authentication apparatus 101 identifies anoperator. The authentication apparatus 101 identifies an operator usinga method such as, as described above, an input operation performed bythe operator or biometric authentication.

In step S102, the biometric sensing apparatus 106 obtains biologicalinformation regarding the operator. The biometric sensing apparatus 106can obtain biological information using, for example, a noncontact CBFmeasuring apparatus, which will be described later. The obtainedbiological information can be, for example, information indicatingtemporal changes in the operator's CBF or information indicatingtemporal changes in the operator's heart rate.

In step S103, the operation sensing apparatus 102 detects the content ofan operation currently performed by the operator and outputs informationindicating the content of the operation. The operation sensing apparatus102 may also calculate a value indicating a load of the operation. Anapparatus other than the operation sensing apparatus 102, namely aprocessor of the signal processing apparatus 108, for example, maycalculate the load of the operation, instead.

In step S104, the signal processing apparatus 108 stores the measuredbiological information, the information indicating the load of theoperation, and time information in the storage device 104 for eachoperator while associating the measured biological information, theinformation indicating the load of the operation, and the timeinformation with one another.

In step S106, the signal processing apparatus 108 compares estimatedbiological information and the measured biological information regardingthe operator with each other. Next, in step S107, the signal processingapparatus 108 determines the operation appropriateness of the operatoron the basis of a result of the comparison. If a difference between avalue of the estimated biological information and a value of themeasured biological information exceeds a certain threshold, forexample, it can be determined that the operation is not appropriate.Alternatively, the operation appropriateness may be determined stepwisein accordance with the difference between the value of the estimatedbiological information and the value of the measured biologicalinformation.

If it is determined that the operator is not appropriate for theoperator, the signal processing apparatus 108 proceeds to step S108. Instep S108, as described above, the signal processing apparatus 108advises or warns the operator or forcibly stops the operation throughanother apparatus such as the display apparatus 107.

The operations in steps S102 to S108 can be repeatedly performed atcertain time intervals, for example, while the operator is performingthe operation. When an operation has been completed and the sameoperation is performed again, data stored in the past is used in stepS105. By using data accumulated for a relatively long period of time,more accurate estimation can be performed.

Especially important points in the embodiment of the present disclosureare as follows.

-   (1) Operation information indicating a load of an operation and    biological information are accumulated in a database for each person    for a relatively long period of time. Data can be repeatedly    accumulated for each operation for a period of time such as several    days, one week, one month, several months, half a year, one year, or    several years.-   (2) Current biological information is estimated on the basis of    accumulated data.-   (3) The estimated current biological information and measured    biological information, which has been actually measured, are    compared with each other, and operation appropriateness at a present    time is determined.

In the present embodiment, a mechanism with which current biologicalinformation can be estimated in real-time by learning changes in anoperation load and changes in biological information is constructed. Asa result, a load on an operator can be estimated more accurately.

A conventional system exists in which a database of biologicalinformation for each person is constructed in order to correctindividual differences and operation appropriateness of an operator isdetermined while correcting individual differences. With a certainoperation in a test environment, that is, with a test in which anoperator performs a test task and a reaction is observed, effectivenessof such a system has been verified. For example, a method is known inwhich a test task in which an operator does mathematical calculations orrecollects related words is assigned to the operator and the operator'sCBF is measured. In an actual operation environment, however, it isdifficult to assign such an operation task during work, learning, ordriving. An operator's mental state needs to be determined from changesin biological information during operations whose loads vary. By asimple method, such as one in which past data is simply averaged or dataobtained under similar conditions is extracted and averaged, however, aneffect of individual differences or an operation load cannot becorrected.

In the embodiment of the present disclosure, a relationship betweenoperation loads and biological reactions for each person is obtainedfrom past data regarding measured values of the operation loads ofactual operations and biological information. A current mental state oroperation appropriateness of an operator is estimated from therelationship between operation loads and biological reactions. A biggestdifference from the conventional system is that correlation betweenoperation loads and biological information for each person is obtainedfrom past measured data and current biological information is estimatedon the basis of the correlation.

Next, an example of a method for measuring biological information willbe described.

In the present embodiment, a stable, accurate biometric apparatus isused to stably determine a mental state. When biological information isconstantly measured during an operation, a sensor in contact with anoperator's body might obstruct the operation. In addition, a contactstate of a contact sensor might change due to motion of an operator'sbody during an operation, thereby decreasing measuring accuracy. In viewof these problems, the noncontact biometric sensing apparatus 106 basedon an imaging device is used in the embodiment illustrated in FIG. 1A.By using the imaging device, noncontact biometric sensing, which doesnot cause awkwardness, can be achieved. In addition, the imaging deviceincludes a large number of pixels arranged in two dimensions and iscapable of obtaining a large number of pieces of biological informationat once. Accuracy can therefore be increased through a process such asaveraging of signals from a plurality of pixels. Furthermore, theimaging device obtains a two-dimensional image signal. Informationregarding differences between biological reactions of different bodyparts can be obtained from the two-dimensional image signal, which ishighly advantageous. It is known, for example, that nasal blood flowdecreases due to psychological stress and accordingly nose temperaturedecrease. When the imaging device is used, nasal blood flow and foreheadblood flow, which is to be compared with the nasal blood flow, can besimultaneously measured. Changes in biological information can thereforebe stably measured.

Whereas the method for obtaining biological information employing animaging device has various advantages as described above, there is alsoa problem. That is, it is difficult to obtain information regarding aninside of a body, which is necessary to determine a state of brainactivity. This is because if an image of a translucent subject such as aliving body is captured, most of information is about light reflectedfrom a surface of the body, and light from the inside of the living bodyis buried. Near-infrared light is more penetrating to a human body thanvisible light and suitable for obtaining information regarding a deeppart of a living body. Even if near-infrared light is used, however,more light reflected from a surface of a living body or the skin thanlight reflected from an inside of the living body is obtained. As aresult, a signal-to-noise ratio decreases, and accurate measurementcannot be stably performed.

In order to increase a ratio of light reflected from an inside of aliving body including biological information and stably obtain thebiological information, light emitted from a light source may bemodulated temporally or spatially. With such a configuration, opticalsignals from a deeper part of a living body can be selectively obtained.

FIG. 3A is a diagram schematically illustrating an imaging methodemploying a light source that emits light having a uniform distribution.FIG. 3B is a diagram schematically illustrating an imaging methodemploying a light source that emits temporally modulated light. FIG. 3Cis a diagram schematically illustrating an imaging method employing alight source that emits spatially modulated light.

In the example illustrated in FIG. 3A, a light source 601 a emits lighthaving a uniform distribution. When the light source 601 a illuminates aliving body 602 and an image of the living body 602 is captured, most ofsignals obtained by an imaging device 603 is a component correspondingto light reflected from a surface of the living body 602. Since a ratioof a component corresponding to light from an inside of the living body602 is too low to achieve sufficient accuracy.

In the example illustrated in FIG. 3B, on the other hand, a light source601 b emits light subjected to temporal modulation. The light source 601b illuminates the living body 602, and a timing at which the imagingdevice 603 captures an image is controlled in synchronization with themodulation of light from the light source 601 b. In this case, timetaken until detection of light after emission of the light can bechanged by controlling a light emission time and a timing of imaging.The time taken until detection of light after emission of the lightdepends on a distance over which the light propagates from the lightsource 601 b to the imaging device 603 via the living body 602. Byappropriately controlling the timings of emission of light and detectionof the light, reflected light having information at any depth can bedetected. By this method, reflected light having information at anydepth of a living body can be selectively detected. As a result,biological information can be detected with a high signal-to-noiseratio.

In the example illustrated in FIG. 3C, a light source 601 c emitsspatially modulated light. The light emitted from the light source 601 cis radiated onto the living body 602, and the imaging device 603 obtainssignals from an area outside a radiated part. If a position of the lightsource 601 c and a detection position are far from each other, the lightreaches the detection position while forming an optical path having anarched shape called a “banana shape”. Detected signals includeinformation regarding light that has passed through a deeper part of theliving body 602 than when the light source 601 a that emits uniformlight illustrated in FIG. 3A is used. The method employing the lightsource 601 c is thus suitable for obtaining information regarding a deeppart of a living body.

Information regarding a deeper part of a living body can thus beobtained by using a light source that emits temporally modulated lightor spatially modulated light and an imaging method that suits the lightsource.

In an embodiment of the present disclosure, a system is designed on thebasis of the following new pieces of knowledge.

-   Use of biological information estimated from a database in which a    relationship between biological information and operation loads is    stored is effective in constructing a practical operation    appropriateness determination system while reducing an effect of    individual differences in biological reactions-   Use of an imaging device including a light source that emits    temporally or spatially modulated near-infrared light is effective    in improving accuracy of obtaining of biological information

Here, near-infrared light, that is, near-infrared radiation, refers toelectromagnetic waves whose wavelengths under vacuum are 700 nm to 2,500nm. The embodiments of the present disclosure are not limited to a modein which near-infrared light is used. By using near-infrared light,however, biological signals can be obtained more accurately.

The embodiments of the present disclosure will be described hereinaftermore specifically. Description unnecessarily detailed, however, might beomitted. For example, detailed description of well-known facts andredundant description of substantially the same components might beomitted. This is in order to prevent the following description frombecoming unnecessarily redundant and facilitate understanding of thoseskilled in the art. The inventor provides the accompanying drawings andthe following description in order for those skilled in the art tosufficiently understand the present disclosure and does not intend tolimit the theme described in the claims.

First Embodiment

An operation appropriateness determination system employing a noncontactCBF measuring apparatus will be described as a first embodiment. In thepresent embodiment, operation appropriateness is determined frominformation regarding changes in an operator's CBF. The presentembodiment is an example in which the operation appropriatenessdetermination system is used to monitor a driver. A target operation isdriving of a vehicle, and the operator is a driver.

CBF measuring apparatuses that measure changes in CBF usingnear-infrared light have already been proposed. In a conventionalmethod, an operator alternates between a predetermined certain task anda break a plurality of times. The certain task is, for example,calculation, memorization, association, quizzes, or the like. The CBFmeasuring apparatuses measure changes in CBF in different periods. Alevel of brain activity can be estimated from data obtained as a resultof the measurement. It is, however, not realistic to repeat such a fixedtask during driving.

In the present embodiment, a driving operation, which is not a fixedoperation, is used as a task instead of a fixed task. Changes in CBF aremeasured during the driving operation. A surrounding environmentconstantly changes during a driving operation. That is, a drivingoperation can be a constantly changing operation. In the presentembodiment, an operation load is estimated on the basis of informationobtained by an acceleration sensor. According to the present embodiment,a driving operation, which is a daily operation, can serve as a taskinstead of a fixed task. In other words, according to the presentembodiment, “taskless CBF measurement” can be performed.

FIG. 4A is a diagram illustrating an example of the configuration of theoperation appropriateness determination system according to the firstembodiment of the present disclosure. As illustrated in FIG. 4A, theoperation appropriateness determination includes a CBF measuringapparatus 401 and an acceleration sensor 403. The CBF measuringapparatus 401 is an example of the above-described biometric sensingapparatus. The acceleration sensor 403 is an example of theabove-described operation sensing apparatus. The CBF measuring apparatus401 measures CBF of a driver 402. The CBF measuring apparatus 401 isprovided in an upper part of a vehicle in order not to enter a field ofvision of the driver 402 in a direction of a windshield on a driver'ssheet side. The acceleration sensor 403 is provided adjacent to the CBFmeasuring apparatus 401. The acceleration sensor 403 monitors conditionsof a driving operation.

The configuration of the CBF measuring apparatus 401 will be describedwith reference to FIG. 4B. FIG. 4B is a diagram illustrating theschematic configuration of the CBF measuring apparatus 401 according tothe first embodiment of the present disclosure. The CBF measuringapparatus 401 includes a light source 601, the imaging device 603, and acontrol circuit 604. The control circuit 604 is connected to the lightsource 601 and the imaging device 603. The control circuit 604 controlsthe light source 601 and the imaging device 603.

The CBF measuring apparatus 401 measures the CBF of the driver 402 in anoncontact manner using the imaging device 603 of a time-of-flight (TOF)type. The light source 601 emits temporally modulated light inaccordance with an instruction from the control circuit 604. The imagingdevice 603 captures an image in accordance with an instruction from thecontrol circuit 604 in synchronization with the emission of light fromthe light source 601. The imaging device 603 captures an image of aforehead of the driver 402, which is a part to be measured. The imagingdevice 603 includes at least one charge accumulation unit that receiveslight and that accumulates signal charge. The imaging device 603typically includes a plurality of change accumulation units arranged intwo dimensions. As a result, a two-dimensional image signal can beobtained.

The light source 601 according to the present embodiment is a lightsource that emits pulsed near-infrared light having wavelengths of 750nm and 850 nm. The light source 601 irradiates the forehead of thedriver 402 with these two types of near-infrared light. The light source601 can be, for example, a laser light source.

The imaging device 603 according to the present embodiment includes animage sensor including a plurality of light receiving elements arrangedin two dimensions. Each light receiving element is sensitive to theinfrared light having the two wavelengths. The imaging device 603therefore obtains two-dimensional images based on the two types ofinfrared light radiated onto the forehead of the driver 402.

The control circuit 604 can measure a distance to a target part on thebasis of time taken for pulsed light emitted from the light source 601to be reflected and reach the imaging device 603. The control circuit604 temporally decomposes an optical signal returning from the foreheadto measure the intensity of an optical component 404 a reflected from asurface of the forehead and the intensity of an optical component 404 bthat has reached a brain of the driver 402 and returned. For example,the control circuit 604 measures the intensity of the two opticalcomponents 404 a and 404 b by controlling a timing of an electronicshutter of the imaging device 603. Changes in the concentration ofoxygenated hemoglobin (HbO₂) and the concentration of deoxygenatedhemoglobin (Hb) in cerebral blood can be measured on the basis of theintensity of the two types of light. The CBF measuring apparatus 401thus measures changes in the concentration of oxygenated hemoglobin anddeoxygenated hemoglobin in the brain using the light source 601 thatemits the light having the two wavelengths. As a result, operationappropriateness of the driver 402 during driving can be determined.

A major role of blood is to receive oxygen from lungs, carry the oxygento tissues, receive carbon dioxide from the tissues, and carry thecarbon oxygen to the lungs. About 15 g of hemoglobin exists in 100 ml ofblood. Hemoglobin bonded with oxygen is called “oxygenated hemoglobin”,and hemoglobin not bonded with oxygen is called “deoxygenatedhemoglobin”. Optical absorption properties are different betweenoxygenated hemoglobin and deoxygenated hemoglobin. Oxygenated hemoglobinabsorbs near-infrared radiation having wavelengths longer than about 830nm relatively well. Deoxygenated hemoglobin, on the other hand, absorbsred light and near-infrared radiation having wavelengths shorter than830 nm relatively well. Absorptance of near-infrared radiation at awavelength of 830 nm is the same between oxygenated hemoglobin anddeoxygenated hemoglobin. A ratio of the two types of hemoglobin or anoxygen saturation level can be obtained from a ratio of the intensity ofinfrared light to the intensity of red light. An oxygen saturation levelis a value indicating the percentage of hemoglobin in blood bonded withoxygen. The oxygen saturation level is defined by the followingexpression.

Oxygen saturation level=C(HbO₂)/[C(HbO₂)+C(Hb)]×100 (%)

Here, C(Hb) denotes the concentration of deoxygenated hemoglobin, andC(HbO₂) denotes the concentration of oxygenated hemoglobin.

A living body includes components other than blood that absorb lighthaving wavelengths of red and near infrared. Temporal variation inoptical absorptance mainly depends on hemoglobin in arterial blood.Changes in the concentration of the two types of hemoglobin and/or ablood oxygen saturation level can therefore be measured on the basis ofvariation in absorptance. Arterial blood ejected from a heart movesthrough blood vessels as pulse waves. Venous blood, on the other hand,does not have pulse waves. Light incident on a living body passesthrough the living body while being absorbed in different layers of theliving body, such as arteries, veins, and tissues other than blood. Atthis time, tissues other than the arteries do not vary in thickness overtime. Light scattered inside the living body, therefore, changes inintensity over time in accordance with changes in the thickness of anartery blood layer due to pulsation. The changes in the scattered lightreflect the changes in the thickness of the artery blood layer and arenot affected by venous blood and tissues. Information regarding arterialblood can therefore be obtained by focusing upon only a varyingcomponent of scattered light. Pulsation can also be obtained bymeasuring a cycle of the component that changes over time.

It is to be noted that the light source 601 that emits the light havingthe two wavelengths need not necessarily be used. For example, if theconcentration of oxygenated hemoglobin alone is measured, for example, alight source that emits near-infrared light having a single wavelengthlonger than 830 nm may be used, instead.

FIG. 5 is a diagram illustrating the configuration of an operationappropriateness determination system 200 according to the firstembodiment of the present disclosure. The operation appropriatenessdetermination system 200 includes an authentication apparatus 201, asignal processing apparatus 208, a storage device 204, and a displayapparatus 206 in addition to the acceleration sensor 403 and the CBFmeasuring apparatus 401. The signal processing apparatus 208 includes abiological information estimation unit 203 and a driving appropriatenessdetermination unit 207. As described above, the acceleration sensor 403functions as an operation sensing apparatus, and the CBF measuringapparatus 401 functions as the biometric sensing apparatus.

The authentication apparatus 201 authenticates a driver, who is anoperator. The authentication apparatus 201 includes an imaging device.The imaging device obtains an image of the driver's face at a beginningof driving. The driver is identified by comparing the face image with aface image stored in the storage device 204 in advance.

The imaging device of the authentication apparatus 201 may be theimaging device 603 of the CBF measuring apparatus 401. In this case, theCBF measuring apparatus 401 also identifies the driver through facerecognition using an image for CBF measurement. The CBF measuringapparatus 401 has a function of a camera. An image based on the opticalcomponent 404a reflected from a surface of the driver's face is similarto an image obtained by a common camera. Personal authentication,therefore, can be easily performed using an image output from the CBFmeasuring apparatus 401. A single apparatus may thus have a function ofan authentication apparatus and a function of a biometric sensingapparatus.

The acceleration sensor 403 monitors current driving conditions andmeasures an operation load on the driver 402. The acceleration sensor403 can monitor not only degrees of acceleration and deceleration duringdriving but also an integral of acceleration, which indicates a drivingspeed, lateral acceleration, which indicates a cornering speed at acurve, and periodic variation in lateral acceleration, which indicateswandering of a vehicle. The acceleration sensor 403 is thereforeeffective in detecting conditions of a driving operation performed bythe driver 402.

It is possible to obtain driving information regarding the vehicle fromthe vehicle in order to detect driving conditions. The “drivinginformation” refers to information regarding temporal changes in adriving operation, such as acceleration, braking, and steering. Thedriving information is an example of the above-described operationinformation. The operation appropriateness determination system 200 mayinclude a communication circuit in order to communicate data with thevehicle. In such a system, not the acceleration sensor 403 but acomputer inside the vehicle functions as the operation sensingapparatus. When the acceleration sensor 403 is used as in the presentembodiment, the system can be constructed at low cost. In addition, thesystem can be constructed simply without integrating different pieces ofinformation for different vehicle models. If information communicationfor automobiles will develop and vehicle information can be obtainedmore easily, driving information can be received from a vehicle moreeasily without providing the acceleration sensor 403 in the operationappropriateness determination system 200.

A method for detecting driving conditions on the basis of an output ofthe acceleration sensor 403 and obtaining a driving load, that is, anoperation load, will be described hereinafter.

As described above, the acceleration sensor 403 can monitor variousdriving conditions during driving, such as acceleration, deceleration,driving speed, cornering speed, and wandering of the vehicle. A drivingload can be calculated on the basis of at least one of these pieces ofinformation. The driving load increases as acceleration or decelerationincreases, vehicle screed increases, or cornering speed increases.Keeping a vehicle stable within a lane also increases the driving load.Wandering of a vehicle indicates that the vehicle is not kept stablewithin a lane. Wandering of a vehicle itself, therefore, is an importantindicator in terms of driving appropriateness. Wandering of a vehiclecan be detected from small periodic changes in lateral acceleration. Incalculation of a driving load, wandering decreases the driving load.This is because stably controlling a vehicle causes a great drivingload. Now, acceleration of a vehicle is denoted by α, lateralacceleration is denoted by β, and a gentle periodic variation componentof the lateral acceleration is denoted by γ. A driving load L(t) isrepresented by expression (1).

L(t)=k ₁|α(t)|+k2∫α(t)dt+k ₃|β(t)|+k ₄|γ(t)|  (1)

Here, k₁ to k₄ are constants, and ∫α(t)dt denotes a vehicle speed.Appropriate values are set to the constants k₁ to k₄ in advance on thebasis of, for example, an experiment.

FIG. 6 illustrates an example of a result of calculation of anacceleration α(t), a velocity v(t), and the driving load L(t) at a timewhen driving operations, namely acceleration and deceleration, have beenperformed. The driving load L(t) can be easily calculated on the basisof expression (1) from data obtained by the acceleration sensor 403. Thedriving load L(t) can be calculated by a processor incorporated into orconnected to the acceleration sensor 403. The signal processingapparatus 208 may calculate the driving load L(t), instead.

The CBF measuring apparatus 401 continuously or intermittently measuresthe CBF of the driver 402 in a noncontact manner using theabove-described method.

FIG. 7 illustrates an example of measured values of changes in adriver's CBF at a time when a driving test of a vehicle was performed ina test course. The driver performed a driving task in whichacceleration, deceleration, and stopping were repeated at a cycle of 40seconds. Hatched sections indicate periods in which acceleration ordeceleration was performed, and white sections indicate periods in whichthe vehicle was stationary. It can be seen that the concentration ofoxygenated hemoglobin (HbO₂) in the driver's CBF increased and theconcentration of deoxygenated hemoglobin (Hb) decreased because of thedriving operation, namely acceleration or deceleration. It can also beseen that there were delays in changes in CBF relative to the drivingoperations. This behavior of the changes in CBF is considered to occurdue to the following mechanism.

First, local neural activity occurs in the frontal lobe due to a drivingoperation, and the amount of oxygen consumed by brain cells increases.In order to supply oxygen to the brain cells, local blood flow insurrounding capillaries increases. At this time, the increase (about 30%to 50%) in blood flow for supplying oxygen is larger than the increase(about 5%) in the amount of oxygen actually consumed. Blood flow and aflow rate increase in the capillaries and venules. Oxygenated hemoglobinrapidly flows, thereby increasing the concentration of oxygenatedhemoglobin and decreasing the concentration of deoxygenated hemoglobin.This is the mechanism of increasing the concentration of oxygenatedhemoglobin and decreasing the concentration of deoxygenated hemoglobin.It is to be noted that since blood flow increases after brain activityand consumption of oxygen, a change in CBF occurs after the brainactivity. As can be seen from FIG. 7, the changes in CBF occurred withdelays of several seconds after the brain activity for the drivingoperations. The delays are important in estimating a current CBF.

The signal processing apparatus 208 accumulates biological informationand a driving load obtained for each person in the storage device 204 toconstruct a database. The biological information estimation unit 203 ofthe signal processing apparatus 208 estimates current biologicalinformation from the accumulated data. The estimated biologicalinformation is a value of the current biological information estimatedfrom past driving loads and biological information regarding the driver402, who is the operator. The operation of the biological informationestimation unit 203 will be described in more detail.

An estimated value of a change in CBF can be calculated by performingconvolution integration on a hemodynamic response function (HRF) and anoperation load obtained from data obtained by the acceleration sensor403. The HRF is a function indicating a temporal change in changes inCBF caused by brain activity. A mathematical expression for the amountof change in CBF is, for example, expression (2).

HRF_(i)(t)*L _(i)(t)=ΔHbO_(i)(t)  (2)

Here, HRF_(i)(t) denotes the HRF of a driver i, L_(i)(t) denotes theoperation load on the driver i, and ΔHbO_(i)(t) denotes the estimatedamount of change in the concentration of oxygenated hemoglobin of thedriver i. A sign “*” denotes the convolution integration. The CBFmeasuring apparatus 401 according to the present embodiment can measureboth the concentration of oxygenated hemoglobin and the concentration ofdeoxygenated hemoglobin. In this example, however, only changes in theconcentration of oxygenated hemoglobin are used as the amount of changein CBF due to brain activity. This is because, as illustrated in FIG. 7,the concentration of oxygenated hemoglobin and the concentration ofdeoxygenated hemoglobin change in a symmetrical manner, and the amountof change in the concentration of oxygenated hemoglobin is larger. Theconcentration of deoxygenated hemoglobin, however, can be used, forexample, to detect an abnormality in measured data. As described above,the concentration of oxygenated hemoglobin and the concentration ofdeoxygenated hemoglobin change in a symmetrical manner as long asmeasurement is performed correctly. If a certain disturbance, namelyvariation in radiated light or a bodily motion, for example, occurs, theconcentration of oxygenated hemoglobin and the concentration ofdeoxygenated hemoglobin can change in the same direction. An abnormalityin measurement can be easily detected by monitoring the concentration ofdeoxygenated hemoglobin, and abnormal data can be removed. It isimportant to note that the HRF HRF_(i)(t) and the operation loadL_(i)(t) change over time.

The HRF HRF_(i)(t) can be approximated by a function indicated inexpression (3).

HRF_(i)(t)=A _(o)((t−δ)/τ)²exp(−((t−δ)/τ)²)  (3)

Variables A_(o), δ, and τ in this expression and k₁ to k₄ in expression(1) representing the operation load L_(i)(t) can be constantlyrecalculated from results of measurement.

FIG. 8A is a diagram illustrating an example of the HRF HRF_(i)(t). FIG.8B is a diagram illustrating an example of the operation load L_(i)(t).FIG. 8C is a diagram illustrating an example of the amount ΔHbO_(i)(t)of change in the concentration of oxygenated hemoglobin.

The amount ΔHbO_(i)(t) of change in the concentration of oxygenatedhemoglobin illustrated in FIG. 8C is calculated using the methodindicated by expression (2) and the functions illustrated in FIGS. 8Aand 8B. A_(o), δ, τ, and k₁ to k₄ are optimized such that a calculatedΔHbO_(i) and ΔHbO_(m), which denotes the measured amount of change inthe concentration of oxygenated hemoglobin, match. Not only current databut also chronological data weighted in a time direction is used for thecalculation. A multivariate analysis is used to determine theparameters. Alternatively, the parameters can be determined accuratelythrough machine learning. The signal processing apparatus 208 learns andoptimizes an expression for estimating biological information inreal-time from a database of biological information and driving loadsfor each person accumulated in the storage device 204. As a result,operation appropriateness of a driver can be accurately determined. Aneffect of individual differences can be removed by creating a databasefor each person, and changes in a person's biological information can beaccurately estimated by accumulating personal data. In addition, bycalculating a load during driving on the basis of data from theacceleration sensor 403, changes in the biological information due to anoperation that changes over time or driving conditions can be estimated.

FIG. 9A is a diagram illustrating estimated values (broken line) andmeasured values (solid line) of changes in CBF during normal driving.FIG. 9B is a diagram illustrating estimated values (broken line) andmeasured values (solid line) of changes in CBF in a state withoutdriving appropriateness. The changes in CBF here are changes in theconcentration of oxygenated hemoglobin. A vertical axis in a left partof FIG. 9A represents change (ΔHbO) in the concentration of oxygenatedhemoglobin, and a vertical axis in a right part of FIG. 9A representsacceleration. A vertical axis in a left part of FIG. 9B representschange (ΔHbO) in the concentration of oxygenated hemoglobin, and avertical axis in a right part of FIG. 9B represents velocity. Changes inCBF are observed after corresponding driving operations suchacceleration and deceleration.

The driving appropriateness determination unit 207 compares estimatedbiological information and actually measured biological information witheach other. If there is no problem in driving appropriateness of adriver, current changes in CBF estimated from a database and measuredchanges in CBF substantially match as illustrated in FIG. 9A. If thereis an abnormality in the driver, on the other hand, a difference largerthan a variation calculated from past data is caused between theestimated value and the measured value of biological information asillustrated in FIG. 9B. In the example illustrated in FIG. 9B, themeasured amount of change in CBF is significantly smaller than theestimated amount of change in CBF. If such a condition continues, thedriving appropriateness determination unit 207 determines that drivingappropriateness is not enough. In this case, the driving appropriatenessdetermination unit 207 alerts or warns the driver 402 or switches adriving mode through the display apparatus 206 or the speaker, which isnot illustrated. For example, the driving appropriateness determinationunit 207 may output a speech sound such as “You look a little tired.Please breathe deeply” to the driver. Alternatively, the drivingappropriateness determination unit 207 may automatically increaseventilation, take in outside air, or issue a warning such as “It'sdangerous. Please stop the vehicle at a safe place”. If the vehicle isprovided with a driving assisting system, the driving assisting systemmay stop the vehicle at a safe place or activate autonomous driving inaccordance with the driving appropriateness of the driver.

The system according to the present embodiment is a standalone drivermonitoring system that can be additionally mounted on an existingvehicle. All the components illustrated in FIG. 1 are mounted on theintegrated system illustrated in FIG. 4A. During these years, vehiclesare becoming more intelligent. Vehicles are provide withhigh-performance arithmetic devices or computers and capable ofdetecting vehicle conditions by integrating information from varioussensors of the vehicles. In addition, vehicles have a communicationfunction such as the Internet and are capable of communicatinginformation with computers outside thereof. In such a vehicle, part ofthe functions illustrated in FIG. 1 can be incorporated into a computerof the vehicle as software. For example, only the biometric sensingapparatus 106 may be achieved as hardware, and the other functions maybe achieved using functions of the vehicle. Some vehicle models canalready have a function of authenticating drivers. Vehicle operationinformation (e.g., acceleration, braking, or steering) detected by acomputer of a vehicle can be used as information output from theoperation sensing apparatus 102. The computer of the vehicle alsoincludes a storage device. Only the biometric sensing apparatus 106,therefore, may be achieved as unique hardware, and the other functionsmay be provided for hardware of the vehicle as software. It is thuspossible to achieve a certain part of the system illustrated in FIG. 1as dedicated hardware and another part of the system as softwareprovided for a computer of a vehicle, in accordance with a type ofvehicle and vehicle conditions.

A driver's driving appropriateness can be stably monitored constantlywhile reducing erroneous detection due to individual differences anddifferences in driving conditions by using the driver monitoring systemaccording to the present embodiment. With this method, the driver can beconstantly monitored through noncontact CBF monitoring without causingawkwardness or a sensation of pressure. As a result, safer, morecomfortable driving becomes possible.

Second Embodiment

An operation appropriateness determination system according to thisembodiment measures an operation stress of an operator. The presentembodiment aims to, for example, detect a state of an operation load onan operator who is engaged in office work in which a computer such as aPC is used, improve operation efficiency, and prevent the operator fromdeveloping mental health problems. The operation appropriatenessdetermination system evaluates mental loads caused by operationsperformed at workplaces. In the first embodiment, an imaging systemincluding a light source that emits temporally modulated pulsednear-infrared light is used to obtain biological information. In thepresent embodiment, on the other hand, an imaging system including alight source that emits spatially modulated near-infrared light is usedto obtain biological information.

During these years, more and more workers are feeling considerableanxiety, worry, or stress about work or working lives. It is thereforedesired to actively maintain and improve mental health at workplaces. Ina currently conducted “stress check”, for example, the following methodis used. First, a worker fills in questionnaires about stress. Bycollecting and analyzing results, a state of the worker's stress can berecognized. Since this method is based on workers' subjective answers,individual differences are large. An indicator of an operation load thatserves as a basis of a more objective determination, therefore, isdesired. A simple measuring method by which a state of stress can bequantified, for example, is desired.

Various biological signals relating to stress are known. Theabove-mentioned biological signals such as variation in a heart rate,nose temperature, the frequency of blinking, a respiratory rate, and thedepth of respiration are known to be related to a state of stress. Aproblem caused when these biological signals are used to check stress isindividual differences in biological reactions. As illustrated in FIG.2, individual differences in biological reactions are large, and thebiological reactions cannot be used as an objective indicator forevaluating stress as they are. FIG. 2 illustrates a result offluctuation in a heart rate due to stress. Other physiologicalindicators known to be correlated with stress cannot be used to directlydetermine a degree of stress only on the basis of measured values,either. As in the first embodiment, individual differences in biologicalreactions, reproducibility, and the stability of operation tasks areproblems to be addressed.

The operation appropriateness determination system according to thepresent embodiment is provided as a measure for addressing theseproblems. As described above, current biological information based on anoperation is estimated from a database of operation loads and biologicalinformation for each person. Current operation appropriateness isdetermined by comparing the estimated current biological information andactually measured biological information with each other. With thesystem according to the present embodiment, changes in an operation loadand biological information are constantly learned, and stress caused bya current operation can be constantly estimated in real-time.

The operation appropriateness determination system relating to anoperation in which a computer such as a PC is used, too, has theconfiguration illustrated in FIG. 1A. Operation appropriateness isdetermined in accordance with the flowchart of FIG. 1B. Since operationappropriateness in an operation in which a computer is used isdetermined in the present embodiment, a computer such as a PC is usedfor an operation. The operation appropriateness determination system canbe operated using arithmetic performance of the computer used in theoperation.

In the present embodiment, only the biometric sensing apparatus 106 isunique hardware among the components illustrated in FIG. 1A. The othercomponents are all stored in the computer as hardware or software. Afteran operator starts a computer operation, operation appropriateness isdetermined in the background of the target operation. The biometricsensing apparatus 106, which is hardware different from the computer, isconnected to the computer. Information obtained by the biometric sensingapparatus 106 is processed by the computer.

A procedure for determining stress will be described specificallyhereinafter with reference to FIG. 1A. In the present embodiment, theauthentication apparatus 101 performs personal authentication on thebasis of an ID input by an operator. For example, personalauthentication is performed when the operator has input an ID and apassword using a keyboard connected to the computer such as a PC. In thecase of a computer used for business purposes, a person is usuallyidentified from an ID and a password input by the person or throughbiometric authentication at a stage of login before an operation isstarted. The system may perform personal authentication using suchpersonal authentication data obtained by the computer.

The operation appropriateness determination system according to thepresent embodiment may also be referred to as an operation stressmeasuring system.

FIG. 10A is a diagram schematically illustrating the overallconfiguration of the operation appropriateness determination systemaccording to the present embodiment. As with the system according to thefirst embodiment, the system includes the CBF measuring apparatus 401 asthe operation sensing apparatus 102. The CBF measuring apparatus 401 isdisposed above a screen of a computer 410 in front of the operator 402.The CBF measuring apparatus 401 according to the present embodimentincludes a near-infrared dot array light source and a near-infraredimaging device. The CBF measuring apparatus 401 measures facial bloodflow of the operator 402. The system according to the present embodimentis capable of monitoring blood flow under a surface of a face, a heartrate, and variation in the heart rate in a noncontact manner.

FIG. 10B is a diagram illustrating the schematic configuration of theCBF measuring apparatus 401 according to the present embodiment. The CBFmeasuring apparatus 401 according to the present embodiment includes alight source 601 c, such as a laser, that projects a dot pattern ofnear-infrared light, an imaging device 603 that obtains a near-infraredimage, and a control circuit 604. The light source 601 c irradiates aliving body (a head of the operator 402 here). The imaging device 603captures an image of the face of the operator 402 irradiated withnear-infrared light. The captured image is analyzed by the controlcircuit 604. The control circuit 604 may be a processor incorporatedinto the computer such as a PC, instead. In this case, the CBF measuringapparatus 401 is achieved by a combination of the processor and thelight source 601 c and the imaging device 603 outside the computer.

A signal processing flow for obtaining biological information from animage captured by the imaging device 603 that obtains a near-infraredimage will be described with reference to FIGS. 11A to 11C.

FIG. 11A illustrates an example of a captured near-infrared image. Sincethe dot array light source is used, bright points corresponding toemission positions of a dot array and relatively weak signals around thebright points are obtained. The relatively weak signals around thebright points are signals corresponding to relatively weak light, whichis radiated light that has entered a body, has been scattered inside thebody, and has returned to a surface. Human skin has a small absorptioncoefficient and a large scattering coefficient for near-infrared light.Light that has passed through a skin surface, therefore, goes throughrepeated multiple scattering inside a body and is output from a widearea of a surface of the body. Alternatively, a light source thatprojects near-infrared light having a line-space pattern or a checkerpattern instead of a dot array pattern, for example, may be used.Similar biological signals can be obtained even when such a light sourceis used.

FIG. 11B is a diagram illustrating an enlarged view of an image of aninformation detection area of a living body. The information detectionarea in this example is a forehead area of an operator indicated by abroken line frame in FIG. 11A. Light 501 scattered inside a bodyreturning from below skin is detected around a projected dot pattern ofinfrared light. Light 502 reflected from a skin surface includesinformation regarding the skin surface, and the light 501 scatteredinside the body includes blood information regarding capillaries insidethe body. Blood flow information inside the body can therefore beobtained by performing calculation while extracting, from image data,only data corresponding to the light 501 scattered inside the body.

FIG. 11C illustrates an example of a heart rate signal obtained in thismanner. Variation in a heart rate or fluctuation in a heart rate can beobtained from the heart rate signal. Furthermore, since an absolutevalue of reflection intensity of light scattered inside a body dependson the amount of blood under a surface, the amount of blood can also becalculated from the signal.

With a conventional biological information sensing system employing acamera, a method has been generally used in which pixel data in theentirety of an area corresponding to a living body part of an image isaveraged and biological information is detected. The biologicalinformation sensing system according to the present embodiment, on theother hand, employs a dot array light source. A component of lightreflected from a skin surface, which is unnecessary, can be removed froma two-dimensional image, and light scattered inside a body, whichincludes biological information, can be selectively extracted. Byefficiently extracting light scattered inside a body, biologicalinformation can be accurately obtained.

It is known that psychological stress can be estimated from temporalfluctuation in a heart rate. When an autonomic nervous system isfunctioning normally, intervals between heartbeats fluctuate. It isknown, however, that the fluctuation in the intervals between heartbeatsbecomes less evident due to stress. Presence or absence or a degree ofpsychological stress can be detected on the basis of changes in thefluctuation in the intervals between heartbeats.

Next, a method for obtaining operation information used by the operationsensing apparatus 102 will be described. In the present embodiment,operation conditions of an operator are detected by analyzing inputs ofthe computer. In the case of a PC operation, the operator inputsoperations to the PC. Operation information can therefore be obtained bymonitoring a type of application used and keyboard inputs or mouseinputs. For example, a history of operation information can be easilyobtained, such as “the content of an operation is a word processoroperation, and the number of characters input in unit time is 50characters/minute” or “the content of an operation is a spreadsheetsoftware operation, and the number of items input in unit time is 30items/minute”. The operation sensing apparatus 102 according to thepresent embodiment is achieved by a combination of the processor in thecomputer and an input device such as a keyboard or a mouse.

Next, the operation of the signal processing apparatus 108 according tothe present embodiment will be described.

FIG. 12 illustrates data indicating changes in an operation load andbiological information regarding an operator in one week obtained by thesystem according to the present embodiment. The content of an operationwas an input operation with a word processor, and the operation load wasthe number of words input. LF/HF, which is an indicator of the activityof the sympathetic nervous system or an indicator of stress, was used asthe biological information. As described above, LF is a low-frequencycomponent of variation in a heart rate, and HF is a high-frequencycomponent. In this example, a range of the high-frequency component wasequal to or higher than 0.20 Hz but lower than 0.35 Hz, and a range ofthe low-frequency component was equal to or higher than 0.05 Hz butlower than 0.20 Hz.

As the number of words input increased and accordingly the operationload increased, LF/HF, which is an indicator of stress, increased asindicated by an arrow 302. When the operator further continued, theoperator felt more fatigued. Operation efficiency decreased, and LF/HFas the indicator of stress further increased as indicated by an arrow301. As described above, however, such a type of reaction greatly variesbetween individuals, and variation in each person is also great. Stressor a degree of fatigue cannot be simply determined only on the basis ofthe number of words input and a value of LF/HF.

In the present embodiment, an average distribution obtained byweighting, along a time axis, data for a relatively long period of timeillustrated in FIG. 12 is created for each operator from a database ofan operation history and biological information regarding the operator.The distribution is used as estimated current biological information. Anaverage distribution for a long period of time represents a relationshipbetween an operation load and biological information unique to eachoperator. This is because it is considered that if there is noabnormality in an operator, actual biological information will becomebiological information having a distribution similar to thedistribution. On the other hand, data regarding operation loads andbiological reactions (e.g., plots in a graph of FIG. 12) obtained as aresult of an operation for a relatively short period of time (e.g.,about one hour) up to a present time is used as measured currentbiological information. The above process is performed by the biologicalinformation estimation unit 103 of the signal processing apparatus 108.The system according to the present embodiment thus uses operation loadsand biological reactions as a frequency map in order to determineoperation appropriateness of an operator.

The operation appropriateness determination unit 105 of the signalprocessing apparatus 108 compares a map of estimated current biologicalinformation, that is, an average distribution for a long period of time,and a map of current biological information, that is, an averagedistribution for a short period of time, with each other. As a result,operation appropriateness of an operator can be determined. If a ratioof data belonging to an area B illustrated in FIG. 12 is higher in acurrent map than in a map of past data, for example, an operation isbeing performed with a high level of operation efficiency. If a ratio ofdata belonging to an area A is high, it is estimated that an operator isnot concentrating on an operation, that is, vigilance is low or theoperator is tired of the operation. In this case, the operationappropriateness determination system displays, on the display apparatus107 (e.g., a computer display), an advice such as “You are losingconcentration. Please stretch and refresh yourself”. If the distributionof current data is mostly concentrated in an area C, it is estimatedthat operation efficiency has decreased due to fatigue. In this case,the system can display, on the display apparatus 107, some advice suchas “You look a little tired. Please take a coffee break”. A decrease inoperation efficiency can thus be detected and some advice can be givenat an appropriate timing by using the system according to the presentembodiment. As a result, high operation efficiency can be achieved.

In addition, by using the system, a sign of deteriorated mental health,such as depression, can be detected. As described above, a relationshipbetween operation loads and biological reactions for a relatively longperiod of time is constantly updated and stored in a database for eachoperator. By tracing variation in distribution for the long period oftime, a sign of depression can be identified. When a depressive tendencygradually appears, the distribution shifts in a direction indicated bythe arrow 301 illustrated in FIG. 12. By detecting such a change in thedistribution, a depressive tendency can be identified. If such atendency is observed, for example, an operator can be encouraged to seean industrial physician. It is known that, in the case of depression,the low-frequency component LF of variation in a heart rate, whichindicates the activity of the parasympathetic nervous system, decreases.Therefore, not only the relationship between LF/HF and the operationload illustrated in FIG. 12 but also a relationship between LF and theoperation load may be monitored. In doing so, a depressive tendency canbe detected more accurately.

The system was actually constructed in a computer terminal of anoperator who input data using a word processor as operations, and datawas obtained for a relatively long period of time. The data was obtainedfor three months. The operator mainly input data using the wordprocessor as operations.

FIG. 13A illustrates a relationship between the number of charactersinput in unit time and LF/HF during input operations obtained from theinput operations for three months. A darker part indicates a higherfrequency. An average input speed was about 75 characters per minute.The value of LF/HF was 1.3 times as high as under normal conditionsunder which the operator performed no operations. This means that theoperator became slightly nervous during the operations. The distributionindicates, for the target operator, a relationship between variation inan operation load and variation in biological information for a longperiod of time. If there is no abnormality in the operator's physicalconditions or mental conditions, the distribution is not significantlydeviated from. Such a distribution is used as estimated biologicalinformation. Operation appropriateness of the operator was determined bycomparing the distribution and current biological information with eachother. A distribution of the number of characters input and changes inbiological information for a short period of time (every one hour inthis example) was obtained as current biological information. During themeasurement for three months, two types of characteristic distributionwere frequently observed. FIGS. 13B and 13C illustrate an example of thetwo types of distribution.

In the distribution illustrated in FIG. 13B, the number of charactersinput is smaller than in the distribution illustrated in FIG. 13A. Itcan be seen that operation efficiency decreased. In this case, LF/HF,which indicates concentration or stress, was also lower. It can beestimated that the operator was losing concentration at a correspondingtime.

In the distribution illustrated in FIG. 13C, on the other hand, thenumber of characters input is smaller than in the distributionillustrated in FIG. 13A, that is, in this case, too, operationefficiency decreased. LF/HF, which indicates stress, however, was higherthan when the operator was performing an operation efficiently. It canbe estimated that the operation efficiency of the operator decreased ata corresponding time due to fatigue from the operation.

As described above, although a decrease in operation efficiency can bedetected by measuring only the operation efficiency, a cause of thedecrease cannot be identified, and an effective measure for improvingthe operation efficiency cannot be found. By using the system accordingto the present embodiment, operation appropriateness of an operator canbe determined, and an appropriate advice can be given in accordance witha result of the determination. As a result, work productivity can beimproved.

As described above, the data indicating the relationship between theoperation load and biological information for a long period of timeillustrated in FIG. 13A is constantly updated with latest data. Byanalyzing changes in the distribution, long-term mental healthconditions of an operator can be checked. If a high-frequency partillustrated in FIG. 13A gradually moves in a direction indicated by thearrow 301 illustrated in FIG. 12, for example, it can be seen that somemental health problem can be arising. It is important especially interms of work safety to identify mental health problems at early stagesand take appropriate measures.

As described above, by comparing a distribution of an operation load andbiological information for a relatively long period of time and acurrent distribution of an operation load and biological information fora relatively short period of time with each other, current operationefficiency and operation appropriateness can be determined. In addition,by monitoring temporal changes in the distribution of an operation loadand biological information for a relatively long period of time,measures can be efficiently taken for mental health problems.

Third Embodiment

This embodiment is about an operation appropriateness determinationsystem that aims to improve the efficiency of learning in which acomputer such as a PC is used. The operation appropriatenessdetermination system according to the present embodiment can also bereferred to as a “learning appropriateness determination system”. Thesystem can be used, for example, in a school, a cram school, or onlinelearning. An operator in the present embodiment is a learner, and thecontent of an operation is learning in which a computer is used.

During these years, a market for various learning systems and learningmaterials employing computers is expanding. Such a system isadvantageous in that a learner can learn at any time he/she likes. Thereis a problem, however, in that because no teacher is present, thelearner tends to lose concentration and it becomes hard to producedesirable results. In order to solve this problem, the presentembodiment provides a system that determines concentration or learningappropriateness of a learner and that gives feedback to the learningduring the learning. In the present embodiment, as in the secondembodiment, a computer is used. Therefore, in the present embodiment,too, the same hardware configuration as that according to the secondembodiment can be used. As illustrated in FIG. 10A, the CBF measuringapparatus 401 is an only piece of unique hardware and connected to thecomputer 410 such as a PC. The components illustrated in FIG. 1A otherthan the CBF measuring apparatus 401 are all stored in the computer 410as hardware or software. After an operator starts a computer operation,the computer 410 determines operation appropriateness in the backgroundof the target operation. Learning software operates in combination withthe system, and content of learning can change in accordance with alearner's understanding and concentration, which achieves efficientlearning.

In the present embodiment, too, personal authentication is performed byinputting an ID using the computer such as a PC.

The hardware configuration of the CBF measuring apparatus 401 is thesame as that according to the second embodiment. As illustrated in FIG.10B, the CBF measuring apparatus 401 includes the light source 601c,which is a near-infrared dot array light source, and the imaging device603. The system according to the second embodiment measures a heart ratefrom changes in facial blood flow and uses fluctuation in the heart rateas biological information. The system according to the presentembodiment, on the other hand, determines concentration from changes innasal blood flow.

A signal processing flow for obtaining biological information from animage captured by the imaging device 603 will be described withreference to FIGS. 14A to 14C.

FIG. 14A illustrates an example of a captured near-infrared image. FIG.14B is a diagram illustrating an enlarged view of an image of aninformation detection area of a living body. In this example, theinformation detection area of the living body is a nose area indicatedby a broken line frame in FIG. 14A. Light 501 scattered under skin isdetected around a projected dot pattern. Blood flow information insidethe body can be obtained by performing calculation while extracting,from image data, only data corresponding to the light 501 scatteredinside the body. FIG. 14C illustrates an example of the blood flowinformation obtained in this manner. When blood flow increases,reflectance decreases due to absorption of light by blood. Changes inthe blood flow can therefore be detected from a signal of reflectedlight. A difference between the signal illustrated in FIG. 14C and thesignal illustrated in FIG. 11C is the width of a vertical axis, that is,changes in reflectance due to variation in a heart rate are smaller thanchanges in blood flow. FIG. 14C illustrates results obtained after aneffect of variation in a heart rate is removed by performing time movingaveraging. FIG. 14C illustrates not only a result of measurementperformed in a nose but also a result of measurement of changes in bloodflow in a forehead, which is data for comparison.

It is known that nose temperature changes due to stress. Anastomosesbetween arteries and veins called “arteriovenous anastomotic vessels”under the control of the sympathetic nervous system are concentrated inand around the nose. Changes in blood flow caused by activation orinactivation of an autonomous nervous system directly influence changesin skin temperature of the nose. When a person is nervous or stressed,the autonomous nervous system is activated, and blood flow decreases. Asa result, the skin temperature of the nose decreases. Psychologicalstress or concentration has been conventionally evaluated by monitoringthe skin temperature of and around the nose through thermography. In thesystem according to the present embodiment, the near-infrared imagingdevice directly evaluates changes in blood flow that cause changes intemperature instead of measuring the temperature. As described above,more arteriovenous anastomotic vessels are concentrated in the nose thanin other body parts, and the blood flow in the nose is greatly affectedby changes in the autonomous nervous system. The blood flow in theforehead, on the other hand, is stable and hardly affected by changes inthe autonomous nervous system and closely related to temperature of adeep part of the body. The system according to the present embodimenttherefore measures both changes in the blood flow in the forehead andchanges in the blood flow in the nose and uses a result of themeasurement of the forehead as a reference. As a result, an effect ofdisturbances such as changes in the illuminance of radiated light andbodily motions can be removed, and presence or absence or a degree ofpsychological stress can be stably detected on the basis of changes inthe blood flow in the nose.

Next, a method for obtaining operation information used by the operationsensing apparatus 102 according to the present embodiment will bedescribed. A learner learns in accordance with instructions fromsoftware (hereinafter referred to as “learning software”) installed on,for example, a PC, a tablet computer, or the like. The computertherefore constantly identifies content of the learning. The CBFmeasuring apparatus 401 according to the present embodiment measureschanges in blood flow at a time when the learning software presents aproblem and the learner answers the problem. The CBF measuring apparatus401 obtains data such as that illustrated in FIG. 14C. When the learnerconcentrates on solving the problem, the blood flow in the nosedecreases, and reflectance of near-infrared light increases.

Next, the operation of the biological information estimation unit 103 ofthe signal processing apparatus 108 will be described. In the presentembodiment, too, the biological information estimation unit 103 analyzesdata regarding operation loads of learners and biological reactions forlong periods of time and constructs a database for each person in thestorage device 104. An operation load in the present embodiment is aproblem solving condition, and biological reactions are changes in theblood flow in the nose. Data regarding time taken until a learner solveseach problem after the problem is presented, the difficulty of problems,and whether the learner has correctly solved each problem can beobtained from the computer 410. The biological information estimationunit 103 calculates an average change in the learner's blood flow in thenose under such conditions on the basis of the data. In the presentembodiment, the average change is used as an estimated value ofbiological information.

The operation appropriateness determination unit 105 of the signalprocessing apparatus 108 compares an estimated current amount of changein the blood flow in the nose and an actually measured amount of changein the blood flow in the nose with each other. As a result, learningconditions of the learner can be detected. If the learner has solved aproblem earlier than estimated and the amount of change in the bloodflow in the nose is smaller than an estimated value, it can bedetermined that the problem is too easy for a current learning level ofthe learner. In this case, it can be determined that a more difficultproblem is to be presented or that the learner is to advance to a nextlearning step. If the learner has solved a problem later than estimatedand the amount of change in the blood flow in the nose is smaller thanthe estimated value, the learner is losing concentration on thelearning. An alert can be issued or an advice to refresh himself/herselfcan be provided on a display of the computer. If the learner has notsolved a problem even though the amount of change in the blood flow inthe nose is large and the learner has concentrated on the problem, it isestimated that the learner's understanding of a range of learning isinsufficient. In this case, a problem for identifying a lack ofunderstanding of the learner can be presented or content of learning canbe changed such that the learner can learn an important part again. Ifthe amount of change in the blood flow in the nose is large, and thelearner has concentrated on solving a problem and solved the problem, itis estimated that learning is going well. In this case, it can bedetermined that a more difficult problem is to be presented or that thelearner is to advance to a more difficult content of learning. Theoperation appropriateness determination unit 105 thus provides a learnerwith learning content according to operation appropriateness inaccordance with a result of a determination made for the learner.

As described above, understanding of learning or concentration can bedetermined as operation appropriateness by using the system according tothe present embodiment. A computer can provide learning content or analert according to a result of the determination of the operationappropriateness of a learner. As a result, the learner can efficientlylearn while maintaining concentration.

The present disclosure also includes a computer program that specifiesan operation to be performed by the signal processing apparatus 108illustrated in FIG. 1A. The computer program is stored in a storagemedium such as a memory in the operation appropriateness determinationsystem and causes the signal processing apparatus 108 to perform theabove-described operations.

What is claimed is:
 1. An operation appropriateness determination systemcomprising: an authentication apparatus that identifies an operator on abasis of a feature of the operator and that outputs information foridentifying the operator; a biometric sensing apparatus that obtainsbiological information regarding the operator and that outputs thebiological information; an operation sensing apparatus that detects aload of an operation that is being performed by the operator and thatoutputs operation information indicating the load of the operation; astorage device; and a signal processing apparatus, wherein the signalprocessing apparatus accumulates, while the operator is performing theoperation, the information for identifying the operator, the biologicalinformation, the operation information, and time information in thestorage device while associating the information for identifying theoperator, the biological information, the operation information, and thetime information with one another, estimates the biological informationregarding the operator at a present time on a basis of a correlationbetween temporal changes in the operation information and temporalchanges in the biological information in past accumulated in the storagedevice, and determines appropriateness of the operator for the operationby comparing the estimated biological information regarding the operatorat the present time and the biological information regarding theoperator at the present time obtained by the biometric sensing apparatuswith each other.
 2. The operation appropriateness determination systemaccording to claim 1, wherein: the authentication apparatus includes aninput device that enables the operator to input a person authenticationcode before performing the operation, and the authentication apparatusidentifies the operator on a basis of the person authentication code. 3.The operation appropriateness determination system according to claim 1,wherein the authentication apparatus includes a biometric authenticationdevice that identifies the operator using at least one selected from thegroup consisting of a fingerprint, a palm print, an iris, and a veinpattern.
 4. The operation appropriateness determination system accordingto claim 1, further comprising: an imaging device that captures an imageof the operator and that obtains data regarding the image, wherein theauthentication apparatus identifies the operator on a basis of the dataregarding the image.
 5. The operation appropriateness determinationsystem according to claim 1, wherein the biometric sensing apparatus isarranged at a point distant from the operator, includes an imagingelement that captures an image including a head of the operator and thatobtains data regarding the image, and obtains the biological informationregarding the operator on a basis of the data regarding the image. 6.The operation appropriateness determination system according to claim 1,wherein the biometric sensing apparatus includes a light source thatemits near-infrared light which is spatially or temporally modulated,and an imaging element that captures an image including a face of theoperator illuminated by the light source.
 7. The operationappropriateness determination system according to claim 6, wherein thenear-infrared light is spatially modulated using a dot array pattern, aline-space pattern, or a checker pattern.
 8. The operationappropriateness determination system according to claim 6, wherein: thenear-infrared light is pulsed light, and the imaging element includes atleast one charge accumulator that receives the pulsed light and thataccumulates signal charge.
 9. The operation appropriatenessdetermination system according to claim 1, wherein the signal processingapparatus estimates the biological information regarding the operator atthe present time by analyzing the correlation accumulated in the storagedevice through a multivariate analysis.
 10. The operationappropriateness determination system according to claim 1, wherein thesignal processing apparatus learns the correlation stored in the storagedevice through machine learning and estimates the biological informationregarding the operator at the present time on a basis of a learningresult.
 11. The operation appropriateness determination system accordingto claim 1, wherein: the operator is a driver of a vehicle, theoperation is driving of the vehicle, and the operation information isinformation regarding an operation for driving the vehicle.
 12. Theoperation appropriateness determination system according to claim 11,wherein the operation for driving the vehicle includes at least oneoperation selected from the group consisting of acceleration, braking,and steering.
 13. The operation appropriateness determination systemaccording to claim 11, wherein: the operation sensing apparatus includesan acceleration sensor, and the signal processing apparatus estimatesinformation regarding the operation for driving the vehicle on a basisof information output from the acceleration sensor.
 14. The operationappropriateness determination system according to claim 11, wherein: thevehicle has an autonomous driving function including driving assistance,and the signal processing apparatus determines content of the drivingassistance in accordance with the appropriateness of the driver andcauses the vehicle to perform the driving assistance.
 15. The operationappropriateness determination system according to claim 1, wherein: theoperation is an input operation in which a computer is used, and theoperation information is information regarding an operation input to thecomputer.
 16. The operation appropriateness determination systemaccording to claim 15, wherein the operation includes at least oneoperation selected from the group consisting of a keyboard input and amouse operation.
 17. The operation appropriateness determination systemaccording to claim 15, wherein the signal processing apparatus causesthe computer to output an image or a sound indicating advice about theoperation in accordance with the appropriateness of the operator. 18.The operation appropriateness determination system according to claim 1,wherein: the operation is learning in which a computer is used, and theoperation information is information regarding content of the learningand an operation performed using the computer.
 19. The operationappropriateness determination system according to claim 18, wherein thesignal processing apparatus causes the computer to provide learningcontent according to the appropriateness of the operator.
 20. A methodfor determining appropriateness of an operator for an operation, themethod comprising: obtaining information for identifying the operator,biological information regarding the operator who is performing theoperation, and operation information indicating a load of the operation;accumulating the information for identifying the operator, thebiological information, the operation information, and time informationin a storage device while associating the information for identifyingthe operator, the biological information, the operation information, andthe time information with one another; estimating the biologicalinformation regarding the operator at a present time on a basis of acorrelation between temporal changes in the operation information andtemporal changes in the biological information in past accumulated inthe storage device; and determining the appropriateness of the operatorfor the operation at the present time by comparing the estimatedbiological information regarding the operator at the present time andthe obtained biological information regarding the operator at thepresent time with each other.
 21. A non-transitory computer readablemedium storing a computer program causing a computer to perform aprocess comprising: obtaining information for identifying an operator,biological information regarding the operator who is performing anoperation, and operation information indicating a load of the operation;accumulating the information for identifying the operator, thebiological information, the operation information, and time informationin a storage device while associating the information for identifyingthe operator, the biological information, the operation information, andthe time information with one another; estimating the biologicalinformation regarding the operator at a present time on a basis of acorrelation between temporal changes in the operation information andtemporal changes in the biological information in past accumulated inthe storage device; and determining appropriateness of the operator forthe operation at the present time by comparing the estimated biologicalinformation regarding the operator at the present time and the obtainedbiological information regarding the operator at the present time witheach other.